1. Field of Invention
The present invention relates in general to the field of electronic packaging. More particularly, the present invention relates to electronic packaging that removes heat from one or more electronic components using a cooling plate assembly having tubing through which a coolant flows and which is flexible when placed and is then “rigidized” to increase burst strength. The present invention also relates to flexible-to-rigid tubing for use in cooling plate assemblies and other applications.
2. Background Art
Electronic components, such a microprocessors and integrated circuits, must operate within certain specified temperature ranges to perform efficiently. Excessive temperature degrades electronic component functional performance, reliability, and life expectancy. Heat sinks are widely used for controlling excessive temperature. Typically, heat sinks are formed with fins, pins or other similar structures to increase the surface area of the heat sink and thereby enhance heat dissipation as air passes over the heat sink. In addition, it is not uncommon for heat sinks to contain high performance structures, such as vapor chambers and/or heat pipes, to enhance heat spreading into the extended area structure. Heat sinks are typically formed of highly conductive metals, such as copper or aluminum. More recently, graphite-based materials have been used for heat sinks because such materials offer several advantages, such as improved thermal conductivity and reduced weight.
High performance computer systems have rapidly migrated toward liquid cooling solutions to effectively remove the massive heat load from the CEC, or central electronics complex. Typically, the CEC of a high performance computer system includes CPUs, RAM and other electronic components that generate copious amounts of heat. Heat is removed from one or more electronic components in the CEC of high performance computer systems using a cooling plate assembly through which a coolant flows. The design of such systems typically calls for flexible tubing incorporating a large number of connections to one or more coldplates/heat sinks.
For example, a plurality of articulated-gap coldplates may be employed in high performance computer systems. Individual articulated-gap coldplates are separately spring-loaded against the top side of each component (or module) to be cooled. These individual articulated-gap coldplates are interconnected with flexible tubing between each coldplate. Such a scheme is disclosed in U.S. Patent Application Publication 2008/0163631 A1, published Jul. 10, 2008, entitled “METHODS FOR CONFIGURING TUBING FOR INTERCONNECTING IN-SERIES MULTIPLE LIQUID-COOLED COLD PLATES”, assigned to the same assignee as the present application. While this option allows for mechanically independent attach solutions for each coldplate/component (or module) combination and allows each coldplate to have a relatively small mass, it greatly increases the risk of leaking, given the large number of flexible tube interconnects. The risk of leaking is amplified when the burst strength of the flexible tube interconnects is sacrificed to achieve the flexibility required to route the flexible tube interconnects.
High performance computer systems may also employ a combination of a fixed-gap coldplate and an articulated coldplate. Typically, the fixed-gap coldplate is positioned over electronic components having relatively low power dissipation, and the articulated coldplate is positioned over one or more high power processor components. These coldplates are interconnected with flexible tubing, such as copper tubing with a free-expansion loop. Such a scheme is disclosed in U.S. Patent Application Publication 2009/0213541 A1, published Aug. 27, 2009, entitled “COOLING PLATE ASSEMBLY WITH FIXED AND ARTICULATED INTERFACES, AND METHOD FOR PRODUCING SAME”, assigned to the same assignee as the present application. This option allows a minimal number of flexible tube interconnects and thereby decreases the risk of leaking (as compared to solutions that require a large number of flexible tube interconnects). Unfortunately, the risk of leaking nonetheless remains when the burst strength of the flexible tube interconnects is sacrificed to achieve the flexibility required to route the flexible tube interconnects.
The choice of material for making the flexible tube interconnects presents a challenge with respect to ensuring adequate reliability. The tubing material must satisfy two requirements that are in conflict with one another: flexibility (determined as the minimum bend radius prior to kinking) and burst strength. In order to achieve the flexibility required to route the tubing through the CEC, the burst strength is often sacrificed (e.g., the tubing wall strength is reduced). It is desirable to be able to maintain tubing flexibility without sacrificing burst strength.
Therefore, a need exists for an enhanced tubing material for use in cooling plate assemblies and other applications.